Process for purifying ionic liquids

摘要

The present process purifies a salt Cat+X−, where Cat+ is any cation and X− is an organic anion having at least 6 carbon atoms. The salt is an impurity in a composition comprising a water-soluble salt (Cat+)nYn−, where Yn− is an inorganic anion or an organic anion, different from X−, with at most 10 carbon atoms. The process involves converting X− into an acid HX by adding an acid (H+)mZm−, forming two phases: an organic phase comprising HX and an aqueous phase comprising the water-soluble salts (Cat+)mZm− and (Cat+)nYn− or acids (H+)nYn−. The organic phase is separated and the aqueous phase passes over a basic anion exchanger which binds Zm− and Yn− and liberates OH−, giving an aqueous mixture comprising Cat+OH−. The organic phase and the aqueous mixture are converted into Cat+X− and H2O, optionally with addition of further HX.

主权项

1. A process for purifying a salt Cat+X−, comprising a cation Cat+ and an organic anion X−, the process comprising:
converting the anion X− by addition of a water-soluble protic acid (H+)mZm− into an acid HX, thereby forming an organic phase comprising HX and an aqueous phase comprising water-soluble salts (Cat+)mZm− and (Cat+)nYn− or acids (H+)nYn−, separating off the organic phase, passing the aqueous phase over a strongly basic anion exchanger suitable for binding Zm− and Yn− and liberating OH−, thereby obtaining an aqueous mixture comprising Cat+OH−, and converting the organic phase and the aqueous mixture into Cat+X− and H2O, optionally with addition of further HX, wherein X− comprises at least 6 carbon atoms, prior to the process Cat+X− is present as an impurity in a composition comprising a water-soluble salt (Cat+)nYn−, Yn− is an inorganic or organic anion different from X− having not more than 10 carbon atoms, n is 1, 2 or 3, and m is 1, 2, or 3.